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T-cell activation, proliferation and selection of the cell death pathway depend on the production of reactive oxygen intermediates (ROIs) and ATP synthesis, which are tightly regulated by the mitochondrial transmembrane potential (ΔΨ m ). Mitochondrial hyperpolarization (MHP) and ATP depletion represent early and reversible steps in T-cell activation and apoptosis. By contrast, T cells of patients with systemic lupus erythematosus (SLE) exhibit persistent MHP, cytoplasmic alkalinization, increased ROI production and depleted ATP, which mediate enhanced spontaneous and diminished activation-induced apoptosis and sensitize lupus T cells to necrosis. Necrotic, but not apoptotic, cell lysates activate dendritic cells and might account for increased interferon a production and inflammation in lupus patients. MHP is proposed as a key mechanism of SLE pathogenesis and is therefore a target for pharmacological intervention.Innate and adaptive immune responses depend on controlled production of ATP and reactive oxygen intermediates (ROIs) in mitochondria. In response to antigenic stimulation, clonal expansion of T and B cells are continuously downsized and potentially autoreactive cells are eliminated by apoptosis. An array of signals through the T-cell receptor (TCR), costimulatory molecules, cell death receptors, lymphokines, and other circulating metabolites, such as ATP, NAD, cADPR, glucose, glutathione, nitric oxide (NO) and ROIs, determine the fate of T cells [1]. T-cell activation and death pathway selection depend on the production of ROIs and ATP synthesis, which are tightly regulated by the mitochondrial transmembrane potential (ΔΨ m ) (Box 1). Disruption of ΔΨ m has been proposed as the point of no return in apoptotic signaling [2] T-cell activation is regulated by mitochondrial ROI productionROIs modulate T-cell activation, cytokine production and proliferation at multiple levels [12]. The antigen-binding αβ or γδTCR is associated with a multimeric receptor module comprising the CD3γδε and TCRζ chains. The cytoplasmic domains of the CD3 and ζ chains contain a common motif, termed the immunoreceptor tyrosinebased activation motif (ITAM), which is crucial for the coupling of intracellular tyrosine kinases [13]. . Thus, expression of cytokines can be selectively regulated by oxidative stress depending on the relative expression level of transcription factors involved (e.g. IL-2 is expressed through a promoter that has AP-1 and NFAT motifs, and IL-4 is expressed through an AP-1-less NFAT enhancer; Figure 1). Redox control of apoptosis signal processingProgrammed cell death (PCD) or apoptosis is a physiological mechanism for elimination of autoreactive lymphocytes during development. Signaling through the Fas or structurally related TNF family of cell-surface death receptors has emerged as a major pathway in the elimination of unwanted cells under physiological and disease conditions [18]. Fas and TNF receptors mediate cell death through cytoplasmic death domains (DDs) shared by both receptors [19]. They ...

Abnormal death signaling in lymphocytes of systemic lupus erythematosus (SLE) patients has been associated with elevation of the mitochondrial transmembrane potential (Δψm) and increased production of reactive oxygen intermediates (ROI). The resultant ATP depletion sensitizes T cells for necrosis that may significantly contribute to inflammation in patients with SLE. In the present study, the role of mitochondrial signal processing in T cell activation was investigated. CD3/CD28 costimulation of PBL elicited transient mitochondrial hyperpolarization and intracellular pH (pHi) elevation, followed by increased ROI production. Baseline Δψm, ROI production, and pHi were elevated, while T cell activation-induced changes were blunted in 15 patients with SLE in comparison with 10 healthy donors and 10 rheumatoid arthritis patients. Similar to CD3/CD28 costimulation, treatment of control PBL with IL-3, IL-10, TGF-β1, and IFN-γ led to transient Δψm elevation. IL-10 had diametrically opposing effects on mitochondrial signaling in lupus and control donors. Unlike healthy or rheumatoid arthritis PBL, cells of lupus patients were resistant to IL-10-induced mitochondrial hyperpolarization. By contrast, IL-10 enhanced ROI production and cell death in lupus PBL without affecting ROI levels and survival of control PBL. Ab-mediated IL-10 blockade or stimulation with antagonistic lymphokine IL-12 normalized baseline and CD3/CD28-induced changes in ROI production and pHi with no impact on Δψm of lupus PBL. The results suggest that mitochondrial hyperpolarization, increased ROI production, and cytoplasmic alkalinization play crucial roles in altered IL-10 responsiveness in SLE.

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SUMMARYCytokines are important regulators of lymphocyte function in SLE. However, the profile of Th1 and Th2 cytokines produced by circulating lymphocytes in human SLE has not been clearly elucidated. The aim of the present study was to characterize the gene expressions of the Th1-type cytokine IFN-g, and the Th2-type cytokines IL-10 and IL-4 in PBMC of 15 patients with SLE and 10 healthy individuals by a semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). Our results showed that expression of IFN-g (P 0´0004) and IL-10 (P 0´002) transcripts were significantly increased in PBMC of patients with SLE compared with healthy controls. By contrast, expression of IL-4 transcripts in PBMC of patients with SLE was significantly decreased compared with the healthy controls (P 0´0008). Primary sources of IL-10 were B cells and monocytes, with variable contribution of T cells as detected in various fractions of PBMC of patients with SLE (P 0´049). These findings support the hypothesis that the enhanced production of IFN-g by mononuclear cells may trigger inflammatory responses, together with the enhanced production of IL-10 resulting in autoantibody production by B cells in human SLE.

This study confirms that IL1A is associated with susceptibility to AS. Association of the other IL1 gene complex members could not be excluded in specific populations. Prospective meta-analysis is a useful tool in confirmation studies of genes associated with complex genetic disorders such as AS, providing sufficiently large sample sizes to produce robust findings often not achieved in smaller individual cohorts.

Nucleosomes are the dominant autoantigens in patients with systemic lupus erythematosus (SLE), and immune complexes involving nucleosomes are the major cause of tissue damage. The activity of DNase I, the enzyme responsible for nucleosome degradation, has been found to be decreased in patients with SLE. However, it is not known whether DNase activity is a clinically useful parameter. The aim of our study was to assess DNase activity in a prospective study of 113 patients with SLE in relation to disease activity and organ involvement. We included two control groups: 9 patients with undifferentiated connective tissue disease (UCTD) and 14 healthy individuals. DNase activity was found to be lower in patients with SLE (63.75% ؎ 12.1%) than in the controls (81.3% ؎ 9.25%) (P < 0.001). DNase activity in patients with UCTD (64.9% ؎ 18.2%; P ‫؍‬ 0.854) did not differ from that in patients with SLE. Patients with SLE had higher antinucleosome antibody titers (356.3 ؎ 851) than the controls (1.44 ؎ 2.77; P < 0.01) or UCTD patients (39.9 ؎ 57.7; P < 0.01). In addition, samples positive for antinucleosome antibodies displayed low levels of DNase activity. Within the SLE group, the presence of renal disease had no impact on DNase activity or antinucleosome antibody titers. Also, the SLE disease activity index showed no correlation with DNase activity. In a longitudinal study of six SLE patients, DNase activity did not follow disease activity or autoantibody titers. Our results confirm that serum DNase activity is decreased in patients with SLE, but we conclude that it is not a clinically useful parameter for the prediction of flare-ups of disease or renal involvement.Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of a wide range of pathological autoantibodies. Those directed against chromatin components, e.g., double-stranded DNA (dsDNA), histones, and the nucleosome, are of paramount pathological importance (6,8,20).Recent studies of patients with SLE suggest the increasing diagnostic importance of antinucleosome antibodies, in addition to antibodies directed against dsDNA (1, 17). These circulating antibodies may form immune complexes with their target antigens, the glomerular deposition of which will lead to the development of renal damage (12,14).The incidence of immune complex-mediated glomerulonephritis (GN) among SLE patients varies from 30 to 60%. Several studies have confirmed that autoantibodies are produced through an antigen-driven T-cell-dependent mechanism (13,23,27). According to this model, the defective clearance of apoptotic cell debris predisposes individuals to SLE through the accumulation of the chromatin components arising from the dying cells (5, 28).DNase I (pancreatic DNase) and DNase II (spleen acid DNase) cleave nucleosomal DNA, which promotes the disposal of circulating nuclear material. DNase I, a glycoprotein with a molecular mass of 30,400 Da, is a cation-binding secretory endonuclease that digests dsDNA in a sequence-dependent manner (24). DNase II,...